Yes, and it cannot not be so - a rotating pressure-dipole generator is a very effective radiator of sound. Helicopters are noisy for what they can lift, and sca

Yes, and it cannot not be so - a rotating pressure-dipole generator is a very effective radiator of sound. Helicopters are noisy for what they can lift, and scaling down the size and multiplying the number of rotors makes it worse. It is a hard problem to solve because there's not much that can be changed, and a lot fewer that haven't been exploited yet. I think this will remain the last problem after all the control and power issues have been solved. All the flying-car makers are coy about how noisy their machines are.